Temporal and spatial high-frequency monitoring of phytoplankton by automated flow cytometry and pulse-shape analysis

时间：2011年9月14日（星期三） 9:30am

地点：曾呈奎楼B-105

报告人：Michel Denis, Laboratoire de Microbiologie, Géochimie et Ecologie Marines, CNRS UMR 6117, Université de la Méditerranée, Centre d'Océanologie de Marseille, 163 avenue de Luminy, Case 901, 13288 Marseille cedex 09, France (michel.denis@univmed.fr)

abstract

Phytoplankton was investigated with automated high frequency submersible flow cytometry to address their short-term variability and their patchiness.

To document the dynamics of flow cytometry cell groups, we deployed a submersible flow cytometer (CytoSub, www.cytobuoy.com) in the Bay of Marseille (North Mediterranean), at 1.5 m depth. This instrument involves pulse shape recording and analysis and can analyse cells (1-1000 µm) and even chains at a flow rate of 8 µl.s^-1. Phytoplankton was monitored in situ every 30 min during summer 2005. The seven clusters resolved in the size range 1-50 µm, behaved as independent entities, suggesting that they could be considered as functional response groups.

The spatial heterogeneity of oceanic phytoplankton distribution was addressed by running the CytoSub on board a 33 m schooner (Fetia Ura, www.seanergies.com) between Azores and French Britany in April 2007. The flow cytometric analysis was triggered every 15 min (spatial resolution of 2.8 km). Five clusters were resolved in the pumped surface water and specific relationships were determined between their distributions within the different water masses sampled during the cruise. The cluster distributions were then compared to the chlorophyll concentrations estimated from satellite ocean-colour data.

The observed variability is critical to explain the impact of intrinsic and extrinsic factors on phytoplankton spatial and temporal distributions.

New underway developments are set to expand the capacities of this emergent approach.